There is major idiocy being spouted over the situation in Fukushima. Most of all, there are a lot of ‘ifs’. I find the speculation/analysis on the internet is becoming too much with most analyses low on actual hard facts.

This video, however, from NHK Japan is a summary of the events at the stricken plant. It goes back as far as the earthquake and the tsunami itself and uses 3D animations to explain what has happened at each of the reactors.

In Reactor 3, for which there is no specific animation, the explosion had identical causes to that in Reactor 1; due to the greater damage I assume it was simply a larger explosion. The highest levels of radiation are coming from Reactor 3 which has been the focus of cooling efforts today, and Reactor 4, where levels have been too high to allow aerial drops of water. I have been trying to find footage from NHK that I watched live today where they explained the dangers of the aerial operations, again using an animation. The drops from 90 metres were far from ideal. They explained that radiation at the preferred height of 30m was ~250 milliSieverts/hr, but at 90m it was 87 mSv/hr (note how quickly that level falls off with distance). From Wikipedia on radiation dosage:

The helicopters (CH-47 Chinooks) have been adapted with additional lead shielding on the floor to protect from radiation, and are advised not to hover. Each run can carry up to 7.5 tons of seawater; they are restricted to flights of 40 minutes in the area to reduce exposure to radiation.

CNN two days ago (link here) talked to a former GE design engineer who resigned in 1975 over what he saw as critical design flaws in the ‘Mark 1’ reactors. He and others were bothered that the Mark 1 containment design had not taken into account all of the loads that could be experienced in an accident that resulted in loss of cooling (a ‘large loss of coolant’ accident such as coolant pipe breakage in the reactor primary system and a release of steam into the containment system itself). In the designs, the steam released was supposed to be condensed to water in the suppression pool (the large torus structure around the reactor base); the designers’ concern was if the structure failed this would mean loss of containment and loss of the source of cooling water for reactor core; therefore there would be the potential for core meltdown.

At Fukushima the cause was different – the loss of back-up power from water inundation and (both ‘drowning’ the back up electrical systems and washing away fuel storage tanks for the diesel generators) – but the effect is the same that operations are unable to cool system in the way it was designed.

Tonight, an electrical cable is reported in place so there is hope of easing the situation:

Japanese authorities have informed the IAEA that engineers were able to lay an external grid power line cable to unit 2. The operation was completed at 08:30 UTC.

They plan to reconnect power to unit 2 once the spraying of water on the unit 3 reactor building is completed.

What about some of that ‘nonsense’. Well, there’s the concern over the “government coverup” over radiation reaching the US (e.g. here). Then there’s the “all nuclear is bad” and then the counter of “look how much these plants can take”: e.g. The Register: “Fukushima is a triumph for nuke power: Build more reactors now!”. Um – just how can the explosions and events in Fukushima be considered ‘a triumph’? That’s just egregious nonsense bordering on pro-nuclear propaganda.

After the triple blow of a massive earthquake, aftershocks, and a tsunami, much of the infrastructure in northeast Japan is reeling, and the energy sector is descending into a significant crisis.

Already, a casualty has emerged: The resurgence of nuclear power as an alternative energy source worldwide has taken a direct hit.

Meanwhile the MSM in the UK has been wheeling out the Government’s Chief Scientific Officer Professor Sir John Beddington for his opinions on the safety of the radiation levels. Now this is where we think ahead a bit. The UK needs nuclear. The government knows this and has committed to it. At some point it will need Prof Beddington to come out and say that the new reactors that will be built in the UK will be inherently safe. No doubt he will announce a review and the appointee will be his choice. So – the question is – who will it be? Perhaps he can ask pal Lord Oxburgh to play another blinder 😉

With regard to the 250 mSv/hour when the helicopters are flying at 30 meters, in the old units this would have been 25 Rem/hour which would correspond to an LD50 dose in about 2 hours. (50% lethality occurs with an acute dose of 450-500 Rem). When approaching sources at this level one needs trained radiation workers equipped with personal and hand held dosimeters.

If my memory serves me, the North Carolina “Yellow Book” limits exposure for radiation workers to a deep-dose of 5 Rem/year, or about 12 minutes at 250 mSv/hour. Surface doses can be much higher. Probably the regulations are a little different in Japan but modern personal dosimeters are well up to the task of providing ample warning when the accumulated dose is reaching specified limits.

If the “Linear” model of radiation was correct one might expect o.5% of individuals exposed to an acute dose of 5 Rem to die (1/100 of the LD50 dose). Fortunately, the odds are much better than that.

Other things being equal the radiation intensity follows an inverse square law which explains why things look much better at an altitude of 90 meters.

I repeat my question from an earlier comment. Why use the wasteful and dangerous method of dropping water from above when the existing plumbing could be used to inject water into the fuel rod storage pools? If that plumbing is damaged, surely temporary plumbing could set up to allow the pumping to be done from a safe distance.

Verity,
Your pump power numbers relate to the main heat engine that has to handle 3 GW of heat for each GWe Nuclear Power Plant.

The problem that the helicopters are trying to solve is to submerge the spent fuel rods in the small storage pools adjacent to each reactor. Normally this is done via small bore pipes (typically 50 mm diameter with a maximum flow rate of ~ 500 liters/minute).

My responsibility for radiation safety oversight ended in 2002 when the old Rem units were being replaced by Sieverts so please excuse my preference for the obsolete units.

Serious symptoms of radiation poisoning can be expected at dosages in excess of 100 Rem (1 Sievert). One of the curious things about ionising radiation is the sudden onset of lethality.

For example there are cases where doses of 50 Rem produced no symptoms at all whereas a dose ten times larger (500 Rem) is likely to cause the death of 50% of affected individuals within a month.

Our understanding of the lethal effects of ionising radiation is based on the nuclear weapons used in 1945 and the many accidents that have happened since.

The deaths of Harry Daghalian and Louis Slotin are well documented. Both are reported to have noticed a “metallic taste” following their exposure to what turned out to be lethal doses of radiation. See:http://en.wikipedia.org/wiki/Demon_core

If you follow the links in the above wiki you can get details of the injuries suffered by the above individuals.

With regard to the 12 minute exposure, that relates to the allowed annual dose for a “Radiation Worker” in North Carolina. We are allowed 5 Rem/year so 250 milli-Sieverts/hour (25 Rem/hour) means that we would have to limit our exposure to less than 12 minutes (1/5 of an hour).

The acute lethal dose is roughly 100 times higher than the allowed annual dose.

It’s very hard to guess what’s happening without speculating. I know, that sounds like something the catcher said a long time ago at a Yankee’s ballgame. Maybe that’s where I heard it. Anyway, as the old saying goes – “Time’s Money! Money Talk’s! Nobody Walks!” and waiting for something to happen takes time and that’s one thing most people don’t have much of these days.

Indeed! I am horrified what happened at Fukushima.
It is beyond my imagination.
I did my doctorate in nuclear law:
the “Liability of owner of nuclear ships”.
That was in the mid of 1970s. (1973-1975)
I studied all the ‘ifs’ and ‘thats’.
I accepted that nuclear power is dangerous.
I regarded it a necessary as long as we have no alternative.
We do not have the alternative today, 30 years later.
Wind and sun is NOT better than nothing, but NOT enough and sufficient.
Without nuclear energy we are at the mercy of
__ serious volcanic eruption (e.g.: Iceland 2010: Eyjafjallajökull), or
__serious interruption (or blackmail) from the middle East.
However, the management at Fukushima is
the worst I could ever have imagined.
See for example the
Press Release (Mar 18,2011), one week after the event occurred:
”Stationing Vice President at Fukushima City and Managing Director at J Village “
AT: http://www.tepco.co.jp/en/press/corp-com/release/11031806-e.html
and that makes the ‘ifs’ raised, are
man-made and totally unacceptable.
Best regards AB

I’ve never been a fan of nuclear power, but I have not opposed it either. Like you I accept that, particularly now, we have little alternative, and we need to embrace it as necessary.

Nothing is ever black and white. There is no panacea, no one perfect source of energy. So, just like historical energy sources, the renewable energies being developed will have a risk or a down side. The Sendai quake/tsunami is though (IIRC) to be a 1000 year event in that region. Suppose (after a successful move to biomass power) we have a 1000 year volcanic event in the Northern Hemisphere and have a ‘year without a summer’ (worse than 1816 in Europe), what would that do? Not only food production, but now the raw material for energy production would be severely reduced. We need a mixture of technologies.

We need the willingness to improve!
That has been lacking!
Research and constructions was on a
low level, for many years.
Man is at its best in trouble.
The Fukushima incident may eventually
be more good than “seriously damaging.”
With regard to incident management, anyhow!
Otherwise a summer without sun (1816),
or the threat of a new little ice age (1976),
would prove it (although may be a little bit late).
We suddenly would be able and willing
to build and to run nuclear plants in hundreds.

This all depends on the nature of the radiation. Is it alpha radiation, beta? Strong beta, strong alpha? Is it I151 (bad stuff), cesium (somewhat bad), radon (not too bad), tritium? Just calling out REM does not tell the story.

Without knowing the nature, we don;t know anything.

Remember, during the fifties, USA, USSR, France and England gave us all a nuclear shower by detonating Gigatons of fission and fusion bombs in the atmosphere. Over a hundred aerial explosions. Some bombs approached 100 Megatons. We can trace the fallout to this day, in cesium, C14, etc., and the background radiation is still raised somewhat.

Last timeI looked, I am pretty old and have not croaked yet. I am full of radioactive isotopes of carbon, sulfur, calcium, trace metals, etc., and they may be beneficial even. I would not use plutonium or radium eye-drops, however.

When Uranium fissions in nuclear reactors a variety of dangerous isotopes are created. Caesium 137 is particularly obnoxious because it has 30 year half life and it emits 0.66 MeV gamma rays. It also emits energetic electrons (Beta rays).

Iodine 151 is dangerous if ingested as it is absorbed by the thyroid.

Strontium 90 is dangerous if ingested as is it absorbed into bones.

The trick is not to get any of this stuff on you. If it does get on you, wash it off ASAP. If you ingest some, that is serious but all is not lost. For example sodium iodide pills ensure that your thyroid is not lacking in Iodine so less of the radioactive isotope will be absorbed.

Verity & Ruhroh,
Ooops. This is more than embarrassing. I lost a decimal point!

A dose of 250 mSv/hour is equivalent to 25 Rem/hour so it would take ~20 hours to accumulate an LD50 dose of 450-500 Rem rather than the 2 hours in my earlier post.

It would take about 12 minutes to accumulate the 5 Rem maximum annual dose for radiation workers in North Carolina.

Also, it is I-131 rather than I-151!

As I get older mistakes of this kind are becoming more common so now I distribute cans of “Bullshit Repellent” to my students. Ten years ago I used to tell them that the mistakes were deliberate to make sure that they were paying attention.

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The elevation of the hockey stick and the whole global warming thing to iconic status makes it a giant with feet of clay – poorly founded and ready to crumble. Time to do some digging…